1. Filed of the Invention PA1 1) Arrange the facing material onto the mold in the opening state of the mold. PA1 2) In closing the mold, the movable mold section stops moving before its complete close-out state with predetermined intervals, but is provided to maintain the stationary state or not be moved back to open the mold. Therefore, the movable mold section remains stationary until completion of the plasticizing function. PA1 3) Fill up the mold with molten resin using an injection apparatus. PA1 4) Start clamping and applying the compressive force toward the mold just before or after the completion of the filling process, so that the resin is spread out in the mold and the mold is filled by the clamping. PA1 5) Reduce the compressive force applied to the mold after filling up the mold with the resin. The movable mold is not retracted during the reduction of the compressive force. PA1 6) Take out the produced laminated molding from the mold by opening after the resin is cooled and solidified. PA1 7) Start successively a preliminary plasticizing for the next injection molding (next shot) when the injection is completed.
The present invention relates to a method of producing laminated moldings utilized for car interior members and the like and, more particularly, to a method of producing laminated moldings intended to improve tactile feeling, quality of exterior and safety because the facing material is produced in an integrated state.
2. Description of the Related Art
Conventionally, a laminated molding covered with a facing material has been used as a car interior member (e.g., inside of a door and the roof, a seat) and the like. In the conventional laminated moldings, there is room for improvement in the quality of moldings and the facing material of the surface of the moldings.
For example, nice tactile feeling can be obtained and higher quality of exterior surfaces can be advanced by attaching raised cloth, thick cloth or similar material to the surface of the laminated moldings.
Otherwise, attaching thick cloth having cushioning characteristics on the surface, can improve safety for a driver and passengers in an automobile.
One means of producing laminated moldings is integrally molding by injecting resin in a molten state into the cavity in which the facing material is already seated. According to such integrated molding, it was not required to attach the facing material optionally, so that the productivity could be increased.
As recommended molding methods to produce such laminated moldings, there has been known in the art, for example, an injection compression molding method, an injection press molding method, a flow-stamping method or the like.
However, the conventional molding methods were known to involve the following disadvantages.
In the injection molding method depicted in FIG. 16, a clamping operation for the mold is started at a time t1 in order to feed the resin in the melting state toward the mold. A compressive force applied to the mold in the clamping operation is maintained at a predetermined pressure value SP until a time t5 when completing the injection molding. The facing material is compressed by an internal pressure of the resin stored in the mold while maintaining a position between the resin and the mold.
Consequently, when the facing material is sheet material such as raised cloth and the like, the characteristic of the sheet material having naturally nice tactile feeling, high quality and the like can degrade with the bowing and the raising of the sheet material as a result of the flat compression of the thick cloth and the like.
Since the facing material made of the sheet material having the cushioning characteristics melts with compression of the resin at high temperature and high pressure, the unique cushioning characteristics of the facing material are degraded when the laminated material is taken out from the mold.
Even if the compressive force is reduced by smoothing the flow of the resin in molding and thickening the thickness of the laminated moldings in order that the facing material is not compressed, the result is an increase in weight and material cost for the produced laminated moldings.
On the other hand, flow-stamping can reduce the internal pressure of the resin being compressed because the resin is supplied into a mold in a bonding state, so that a maximum flow distance of the resin in the mold becomes short. However, much time is needed for supplying the resin in the bonding state and the appearance of the produced laminated moldings tends to be inferior because the whole facing material solidifies in the compressed state if only a part of the facing material is solidified first as the surface of the resin solidifies by cooling.
The flow-stamping method includes a mechanism to take a nozzle in and out to flow the resin in the bonding state toward the mold, which should be accompanied with an interacting control system and requires a long molding cycle with much time needed for taking the nozzle in and out, so that the cost for producing becomes higher due to the molding apparatus having large-scale structure.
The disadvantages of the foregoing description are not always produced only in the laminated moldings used for the car interior members and the like but also in general laminated moldings covered the surface of the resin with the facing material.
It is an object of the present invention to provide the producing method of the laminated moldings intended to mold integrally the facing material.